Disadvantages –
The motion is not a continuous 3D motion and the speed is much slower as compared to an xyz-gantry using 3 motors. In this setup, it is impossible to travel from point (x1, y1, z1) to (x2, y2, z2). Instead it travels as follows – (x1, y1, z1) -> (x2, y2, z1) -> (x2, y2, z2).